Fix bug: Let parser match longer argument first

[ace-wu]

a quick patch that fix following bug:

http://localhost> --session-read-only test
Syntax error near "--session-"
http://localhost> --auth-type test
Syntax error near "--auth-typ"

after applying the patch:

http://localhost> --session-read-only test
http://localhost> --auth-type test
http://localhost> httpie
http --auth-type test --session-read-only test http://localhost --session-read-only=test

[eliangcs]

@ace-wu thanks a lot for the bugfix! Can you also add a test case for it?

[ace-wu]

@eliangcs sure! 😸 updated

[eliangcs]

Merged. Thanks for your PR 👍